The present invention relates to motor-operated hospital beds having an articulated support frame, wherein a head section of the frame can be selectively raised and lowered.
Motorized operated hospital beds are conventional in which the head and leg sections of an articulated frame can be selectively raised and lowered by one or more electric motors. In this fashion, a patient's back and/or legs can be adjusted to a desired inclination. Exemplary of such a hospital bed is the disclosure in U.S. Pat. No. 4,097,940 issued to Tekulve et al on July 4, 1978, the disclosure of which is hereby incorporated by reference as if set forth at length herein.
The actuating mechanism for the head section of the articulated mattress frame may include an electric motor which rotates an elongated threaded shaft. A nut is threadedly mounted for longitudinal movement along the shaft and is fixed against rotation relative thereto. Thus, rotation of the shaft produces longitudinal travel of the nut. A linkage interconnects the nut and the head section of the articulated frame in such a way as to convert longitudinal motion of the nut into rotational movement of the head section, thereby altering the inclination of the latter. The motor can be deactivated at any time to hold the head section in a given position of adjustment.
Typically, relatively high-torque, slow-speed electric motors are employed which impart a slow, gentle motion. However, such slow-speed motors are disadvantageous in the event of an emergency requiring immediate treatment of the patient in a fully reclined, horizontal position, such as in the case of heart stoppage, for example. Any undue delay in positioning the patient in the proper posture for treatment can produce serious consequences.
It is, therefore, an object of the present invention to minimize or obviate problems of the above-discussed sort.
Another object of the invention is to enable the head section of an articulated bed frame to be rapidly lowered to a retracted, horizontal position.
A further object of the invention is to provide for such rapid lowering without eliminating the slow, gentle motion produced during normal raising and lowering of the head section.
An additional object of the invention is to provide a manually actuable over-ride mechanism which permits lowering or raising of the head section of the frame independently of the tilt motor.
A further object is to permit the head section to be raised or lowered independently of the motor in the event of an emergency, electrical failure, or operational malfunctions in the drive train.